Metal halide perovskites are a promising class of materials for next-generation photovoltaic and optoelectronic devices. The discovery and full characterization of new perovskite-derived materials are limited by the difficulty of growing high quality crystals needed for single-crystal Xray diffraction studies. We present the first automated, high-throughput approach for metal halide perovskite single crystal discovery based on inverse temperature crystallization (ITC) as a means to rapidly identify and optimize synthesis conditions for the formation of high quality single crystals. Using this automated approach, a total of 1928 metal halide perovskite synthesis reactions were conducted using six organic ammonium cations (methylammonium, ethylammonium, nbutylammonium, formamidinium, guanidinium, and acetamidinium), increasing the number of metal halide perovskite materials accessible by ITC syntheses by three and resulting in the formation of a new phase, [C2H7N2][PbI3]. This comprehensive dataset allows for a statistical quantification of the total experimental space and of the likelihood of large single crystal formation. Moreover, this dataset enables the construction and evaluation of machine learning models for predicting crystal formation conditions. This work is a proof-of-concept that combining high throughput experimentation and machine learning accelerates and enhances the study of metal halide perovskite crystallization. This approach is designed to be generalizable to different synthetic routes for the acceleration of materials discovery.
Using, urea, one of the cheapest chemicals and convenient deamination polycondensation (solvent-free, catalyst-free, one-pot, one-step) provides an industrially relevant and environmentally benign synthesis of branched polyurea. Inspired by the structural analysis of traditional resin adhesives, we hypothesized that the higher the cross-linking degree of the adhesive after curing, the better the bonding performance. Improving the branching cross-linking degree of resin adhesives is the key to improve their bonding performance. In this work, in order to verify the relationship between the branching degree of the polymer adhesives and their bonding properties, branched polyureas with different branching degrees were designed and synthesized. Five polyamines of PA4N, PA5N, PA6N‑1, PA6N‑2, and PA7N were synthesized from ethylenediamine, diethylenetriamine, tris(2-aminoethyl)amine, triethylenetetramine, and tetraethylenepentamine, respectively. Polycondensation of urea with polyamine (PA4N, PA5N, PA6N‑1, PA6N‑2, and PA7N) by deamination achieved branched polyureas including PA4N–urea, PA5N–urea, PA6N‑1–urea, PA6N‑2–urea, and PA7N–urea via a solvent-free, catalyst-free, one-pot, and one-step approach. The polyureas were detailedly investigated as robust adhesives for wood bonding. The bonding performance of the branched polyureas, including PA4N–urea, PA5N–urea, PA6N‑1–urea, PA6N‑2–urea, and PA7N–urea, was represented by lap shear strengths of 1.52, 2.08, 2.23, 2.36, and 2.64 MPa for poplar wood after soaking the specimens in boiling water for 3.0 h, respectively, which indicated the superior lap shear strength and enhanced water resistance for use as a wood adhesive. As we expected, the results showed that the bonding strength of branched polyurea increased with an increase of the number of terminal functional groups. Besides, the adhesive performance on other substrates, including glass, aluminum, stainless steel, and polyvinyl chloride, was also studied, and the adhesion strengths to glass, aluminum, stainless steel, and polyvinyl chloride are 3.52, 3.29, 1.45, and 1.25 MPa, respectively.
Palm boards are often used as a nonverbal measure in human slant perception studies. It was recently found that palm boards are biased and relatively insensitive measures, and that an unrestricted hand gesture provides a more sensitive response (Durgin, Hajnal, Li, Tonge, & Stigliani, Acta Psychologica, 134, 182-197, 2010a). In this article, we describe an original design for a portable lightweight digital device for measuring hand orientation. This device is microcontroller-based and uses a micro inclinometer chip as its inclination sensor. The parts are fairly inexpensive. This device, used to measure hand orientation, provides a sensitive nonverbal method for studying slant perception, which can be used in both indoor and outdoor environments. We present data comparing the use of a free hand to palm-board and verbal measures for surfaces within reach and explain how to interpret free-hand measures for outdoor hills.
The detection of pesticides has become a very important and critical research area because of the rapid development of agriculture and strict environmental protection regulations.
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